Gas alarm sounding

[waterwings]

I have just had shore power and a battery charger fitted to my boat, the first night after the work was compleated I was staying on board and the gas alarm intermittently kept going off.
So up I got, disconnected the gas bottle vented the boat before going back to sleep, to be woken up again by the alarm.
Never having any problems with the alarm before I suspected the batteries are venting off whilst being charged.
The next day carried out some investigation gas bottle connected, charger off no alarm. Gas bottle disconnected, charger on, alarm ringing.

Is this the probable cause and if so how can I prevent this in the future?

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[bedouin]

Whereabouts is the Gas Alarm sensor fitted in relation to the batteries?

I would be a little surprised if gassing of the batteries were the problem. Hydrogen is a very mobile gas which tends to escape very quickly in anything other than a sealed environment, and being lighter than air will not collect in the bilges the same way Butane/Propane/Petrol vapour will.

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[Stemar]

No expert, but I believe that under some cicumstances, not sure what they are, batteries can give off hydrogen sulphide, which is around the same density as air, or maybe a little more.

Could this be what is setting it off?

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[waterwings]

The batteries and gas alarm are at the same height but about six feet apart. The gas alarm is located just above the sole boards in the galley area and the batteries are under one of the bunks in the saloon at floor level.
The boat is an average 35 footer, I hope this will give you the lay out we are talking about.

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[Robin]

Gas bubbling off the batteries WILL set off the alarm, we had that happen on our old battery charger when I turned up the float volts a tad too much. This was an old fashioned so called smart but actually quite stupid charger where you could only increase the charge volts if the float volts went up too, our new charger is a not quite so dumb.

What kind of charger is installed? Some have different charge volt settings to suit different battery types (wet lead/acid or gel type etc), maybe yours has either the charge or the float voltages set too high, or is even faulty. Can you check the voltage under charge with a digital multimeter? You should not be getting gassing, because that will eventually boil off the water in the batteries, plus hydrogen is a fire risk, if it builds up and there is a spark......

<hr width=100% size=1><font size=1>Sermons from my pulpit are with tongue firmly in cheek and come with no warranty!</font size=1>

 

[catmandoo]

I had same problem But no leaks in gas supply . Worked out later was due to unsuccessfull attempts to light oven with gas accumulating in bilges

ON THE OTHER HAND

could it be something like this

try this address

http://www.2step.dk/images/pic_2002-12-05_000019.swf



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[LORDNELSON]

I heard of a case last year where diesel fumes were setting off the gas alarm, might be worth a check. Sea water from a leaky engine hose set off my alarm about two years ago, but one tends to quickly notice events of this kind!

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[pappaecho]

What is the voltage of the battery - my gas alarm has a low voltage setting and goes off to warn of the battery below 9 volts - like you had the same problem... last summer, and found that the fridge had depleted the battery! Warm beer = no gas alarm!

<hr width=100% size=1>Def: Yachting - a way of spending the kids inheritance

 

[boatmike]

You have to ask yourself if this is a real or false alarm. I just "deep sixed" a PILOT gas alarm because it was going off at random times. There was absolutely no gas as it was switched off at the bottle and the batteries are nowhere near. I didn't even fart near the bloody thing! They are notoriously unreliable and having one does not necessarily ensure you don't have a gas leak anyway! I now rely on a very visible bubble tester which I check regularly and a solonoid actuated valve at the bottle end which gets switched off from a point near the cooker whenever the gas is not in use. Prevention is better than cure I think!

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[charles_reed]

Gas alarms

Many years ago I was presented with a gas alarm by a friend after I'd replaced the maddening Origo alcohol cooker with a high pressure butane one.

We were tied up to a raft, about 3 boats out on the quay at Weymouth. At that time it was permissible for cars to park on the quay. During the evening the gas alarm went off about 12 times - it wasn't till about the 6th time that we became blasé and the 8th time that we found it happened about 10 minutes after a parked car satrted up and drove off.

The only time I've had a real gas leak my nose detected it before the gas alarm - a total disaster, no tea on a trip up from St Evette, through the Raz du Sein and chenal du Four, across the Channel, up past Longships and the Bristol Channel. Only found the leak after daybreak off St David's head - a crack where the flexible to the gimballed stove left the solid pipe - replaced later with armoured "outdoor" piping for propane installations.

So I've limited time for those alarms, set for maximum sensitivity you get loads of false alarms - set so they don't drive you round the bend and they're well-nigh useless.

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